もんじゅナトリウム漏えい事故の原因究明 IHX入口温度計ウェル調査報告書

Investigation on the sodium leak accident of Monju; Research report on the thermocouple well at the inlet of the IHX

青砥 紀身 ; 天藤 雅之; 木村 英隆; 堀切 守人; 小峰 龍司; 平川 康 

Aoto, Kazumi; not registered; not registered; not registered; not registered; Hirakawa, Yasushi

高速増殖原型炉-もんじゅ-2次主冷却系Cループ中間熱交換器(IHX)出口温度計からのナトリウム漏えい事故に関連して、当該温度計破損部の原因調査に資するため、同2次系CループIHX入口部の温度計ウェルを調査した報告(概要)である-調査は、主に熱電対ウェル段付部の損傷調査およびウェル管台溶接部の健全性に関する情報を得る目的で種々の試験検査を実施した。試験検査は、温度計、ウェル段付部、太径および細径ウェル部ならびにウェル-管台溶接部等で、以下に示す通りである。(1)精密寸法計測(2)ウェルの打振試験(3)各部非破壊検査(4)成分分析(5)金属組織観察(6)ウェル段付部の詳細観察(7)硬さ試験(8)隙間腐食に関する調査(9)ウェルの強度特性試験(10)シース高温曲げ試験

This report describes the check of the thermocouple well at the inlet of the intermediate heat exchanger (IHX) of C-loop of the secondary heat tansfer system of the prototype fast breeder reactor Monju, regarding the sodium leak accident of the thermocouple well at the outlet of the IHX of the same loop of the secondary heat transfer system of the same plant Monju. Various tests and inspections were performed to check damages at the part with rapid diameter change of the thermocouple well where stress concentration may occur, and to get the information about the integrity of the welded part between the thermocouple well and the attachment. The thermocouple well, the rapid diameter change part, larger and smaller part, respectively, of the thermocouple well, and welded part between the thermocouple well and the attachments were examined as written below. (1)Accurate measurement of the dimension. (2)Vibration test by tapping the thermocouple well. (3)Non destructive testing at some points. (4)Chemical composition analysis. (5)Microscopic observation of metalogical structure. (6)Detailed observation around the rapid diameter change part. (7)Hardness test. (8)Research on corrosion at the clearance. (9)Structure strength test of the thermocouple well. (10)Bending test of the thermocouple's sheath at high temperature.